The most random bugs happening unexpectedly after the finishing touches during the last round of testing, because the level is too big and went over some unknown limits... And lots of other things, I always manage to run into something strange.

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That's probably the only software I don't really mind crashing because you can make a backup everytime, so you just have to re-open NGLE and load that backup and continue building like nothing happened.

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"Everytime you use WadMerger's Sound Manager, a kitten drowns in a poop pool."